Spray gun



SPRAY GUN Filed Sept. '7, 1926 2 Sheets-Sheet 1 Zr van for; jerk June21, 1927.

B. R. SAUSEN- ET AL SPRAY GUN Filed Sept. 7., 1926 2 Sheets-Sheet 2,TZ/ZZ QJ 20 4/ I :8 M t 0w Sm BIC F M Efqar 5.041!) Patented June 21,1927.

UNITED "STATES BERT R. SAUSEN AND EINAB E. OLSEN,

LESS PNEUMATIC SYSTEMS INC., OF CHICAGO,

SPRAY GUN.

ILLINOIS,

OF CHICAGO, ILLINOIS, ASSIGNOES T0 REEB- ILLINOIS, A CORPORATION 0]Application filed September 7, 1926. Serial No. 134,114.

Our invention relates to the class of spraying appliances designed forprojecting liquids in the form of a finel divided spray of predeterminedform. an density, such as the so-called spray for spraying paints,varnishes and the like.

Where such a coating material is to be applied in a uniformly densedistribution to surfaces of large area, it is customary to employ aspraygun in which the paint or other liquid is first projected in acylindrical stream and is then flattened by jets of airdirected againstopposite sides of the projected stream. To keep the projected streamfrom enlarging in diameter before it is reached by the attening jets ofair, this stream is commonly housed by a tubular sheath of air which isprojected through an annular spacebetween the paint nozzle and the boreof an air nozzle. In practice, the paint nozzle and the air nozzle areusually supported independent of one another,and unless great accuracyis employed in the construction of the ap liance, these two nozzles arenot coaxial. hat is to say, the two nozzles may have'their axes parallelbut relatively shifted, or these .axes may be at an angle to each other.In every such instance the tubular air sheath is not uniform inthickness and hence will permit the stream of liquid within it to spreadout of a true cylindrical section, so that the flattenin air jets willnot produce the desired uniformity in fan of spray.

Moreover, the air ports for the flattening air jets are usually formedin the samevair nozzle which has its bore defining the initial contourof the tubular sheath of air, so that any relative shifting or tiltingof the axis of the air nozzle with 'respectto the axis of the paintnozzle spoils the symmetry of the flattening air jets with respect tothe stream of paint projected'through the axial bore'of the paintnozzle. This also alters the distribution of the spray inthe resultingsheet or fan of spray.

Our present invention aims to overcome both of these difiiculties byproviding a spray-appliance head construction in which g the air nozzleis accurately almed and oen-.

tered b the liquid nozzle, and aims to accomplis this in a constructionwhich will constituent parts.

guns employed the resulting sheet or not require an unusual degree ofaccuracy in the manufacture or assembling of the Furthermore, ourinvention aims to provide a spraying appliance of this class in whichthe air nozzle is clamped upon the liquid nozzle by an attaching collarand in which the ports for the flattening jets of air are formed byrooves out either in the exterior of the liquid nozzle or in the bore ofthe attaching collar. In the constructions of that type, it is importantthat the joint between the attachin collar and the paint nozzle be tihtly sea ed except forthe said grooves, an particularly adjacent tothese grooves, as any air issuing forwardly at other points of thejunctures between these two nozzles will project spray inv undesireddirections so as to produce oil spray spottings which mar the uniformityof the resulting coating.

Illustrative of our invention Fig. 1 is a central, vertical andlongitudinal section through the forward portion of a spray gun designedfor producing aflat spray and embodying our invention.

'Fig. 2 1s an'enlargement of the forward portion 9f Fig. 1, with theliquid nozzle shown in section.

' Fig. 3 is a side elevation of the air nozzle of this spray gun.

Fig. 4 is front elevation of this air nozzle member. I

Fig. 5 is a section similar to the forward portion of Fig. 1, showinganother embodiment of my invention, namely one in which an auxiliarysleeve secures the attaching collar to the body of the spray gun, and inwhich the grooves for the flattening air jets are cut in the bore of theattaching collar. Fig. embodiment in which 6 is a similar section,showing an the ports for the flattoning air jets are formed by boresextending throu h parts of the air nozzle.

"Fig. 7 is a ragmentary section along the line of 5-5 of Fig. 5.

In the embodiment of Figs. 1 to 3 inclusive, the forward or head end ofthe spray un bod 1 has a longitudinal bore 2 through which e aint issupplied and a separate passage 3 {hr the compressed air. The forwardend of the bore 2 is threaded to match the male thread on the rearportion 4 of a liquid nozzle 4 which has an axial bore 5, and theforward end of this paint nozzle 1s contracted in diameter to form atubular liquid outlet 6. The forward portion of the bore 5 iscorrespondingly contracted and has a forwardly tapering bore portionaffordin a tight seat for the tapering forward end of the usual needlevalve stein 7 which controls the discharge of the paint or other li uid.

e exterior of the liquid nozzle 4 has a forwardly taperingfrustro-conical portion 4 disposed between the threaded rear portion 4*and the paint outlet 6. Sleeved upon this tapering portion 4: is an airnozzle which is here shown in the form ,of a perforate cap comprising atubular rear portion 8 bored to fit the taper of the said exteriornozzle surface 4 and a head 9 having a bore 10 somewhat larger indiameter than the exterior of the tubular liquid outlet 6. This liquidoutlet extends into, and desirably entirely through the said bore 10 soas to leave an interposed annular port 14 through which the tubular airsheath is projected. To supply air for this sheath, we provide thetubular portion 8 of the nozzle member with perforations 11 leading toaspace 12 back of radially outer part of the head 9 and in front of aportion of the air nozzle. These perforations 11 preferably have theiraxes in planes radial of .the nozzle member and we desirably provide alarge number of such perforations, all leading to an annular space 24behind the head 9 and in front of apart of the air nozzle 4. By doingso, we can utilize this space 24 as an air supply chamber for projectinga tubular air sheath at high pressure through the annular air port 14,while making this port 1 1 so narrow (radially of the nozzle) as torequire a comparatively small amount of air for the tubular air sheathprojected through it.

To hold the air nozzle member socketed upon the tapering part of theliquid nozzle, we employ a retaining collar which snugly fits a part ofthe air nozzle so as to aline itself with the latter, and we secure thiscollar to the body member of the spray gun by attaching means which willpermit the collar to adjust itself to this alining. With this in mind,Fig. 3 shows the air nozzle as having its forward peripheral surfaceportion 15 of a forwardly tapering frustroconical shape, this surfacebeing coaxial with the taper in the tubular part 8 and the bore 10. Fig.1 also shows the attaching collar as comprising a tubular rear part 16and a forwardly tapering contracted end 17 which is bored out to haveits rear face match the taper of the portion 15 of the air nozzlemember. The rear end of the main collar part 16 is threaded upon theforward end of the gun body 1, and this threaded connection issufficiently loose so that the collar can rock or shift slightly on thegun bod Iii assembling the parts as thus described, the tapering fit ofthe air nozzle member on the liquid nozzle accurately alines these partswith each other, thereby disposing the bore 10 of the air nozzle membercoaxial with the cylindrical exterior of the tubular liquid outlet 6.Hence the air forced through the annular port 14 issues in the form ofan annular sheath of uniform thickness and accurately concentric withthe liquid projected through the bore of the liquid outlet 6.

When the collar has its rear end screwed under the gun body, thetapering rear face of its contracted forward end 17 seats upon thetapering surface portion 16 of the air nozzle "and automatically alinesthis collar with both the air nozzle and the liquid. outlet, while alsoinsuring a tight' seal between the collar and the air nozzle. Thetightness of this sealing also permits us to form the ports for theflattening air jets by grooves extending along the juncture of theinter-fitting tapered surfaces of the portions 15 and 17 in planesradial of the air nozzle member.

This we preferably accomplish by milling a pair of grooves 18 in thetapering portion 15 of the air nozzle, with the axes of the grooves in acommon plane radial of this nozzle member and with the groovesdiametrically opposite each other. By using a milling tool for cuttingthese grooves, we can readily secure groove edges free from burs andrunning snugly up to the inner face of the collar, thereby avoiding theissuing of any stray air such as would produce an off spray. So also, bymerely providing a slight looseness of the threaded connection betweenthe collar and the gun body,

we readilypermit the needed accurate alini ing of the heretoforedescribed tapering portions without requiring the threading to he soloose as to permit air to issue at this connection, although any suchleaking air would issue rearwardly and hence could not affect the spray.

By initially constructing the paint nozzle separate from the gun body,we facilitate the accurate-machining of this part. However, we do notwish to be limited to this or other heretofore described details ofconstruction and arrangement, since many changes might obviously be madewithout departing either from the spirit of our invention or from theappended claims.

For example, the liquid nozzle 4 might be made integral with the gunbody, as shown in Fig. 5, and the ports for the flattening air jetsmight be formed by grooves 25 milled in the tapering rear face of theforward collar portion 17 such as the grooves vided by a loosethreading. Instead, we may provide the collar at its rear end with anoutwardly directed annular flange 20, as shown in Fig. 5,and may securethe collar to the gun body by an auxiliary collar 21 which is threadedat its rear end upon the gun body 1 and which has a contracted forwardend 21 engaging the front of the flange 20, this flange having a borelarger than the adjacent main portion lo of the collar. In

this case, we can readily inter-pose a packing rin 22 between the rearend of the collar an the forward end of the gun body 1', as also shownin Fig. 5, so as to obtain a tight sea'l'between these parts.

With each-of the illustrated embodiments, the width of each port for theflattening air (namely, the width of each groove 18 or 18, or thediameter of the bores 19) is preferably a 'little narrower than the boreof the paint outlet. By using this proportion, we avoid disru ting theliquid stream unduly through a g ancing action'of the lateral edgeportions of the flattening air jets, while also avoiding a 'splittin ofthe stream such as would occur ifthe flattening jets of air wereconsiderably narrower than'the diameter of this stream. However, boththe dimensions of the grooves (or diameters of the ports if bored) andthe radial width of the annular air port 10 may be varied according tothe viscosity of the paint or other material which is to be sprayed. Byusing relatively long grooves with sides parallel to, but at opp0- sitesides from, a plane radial of the pro-' jected stream of liquid, we canaccurately predetermine the widths of the flattening jets of air, whichwe have not found feasible with bored air ports owing to the fact thateven a minute enlargement of such a bore at its outlet has amaterialeffect on the crosssection of the issuing jet of air.

Furthermore, by forming two grooves of uniform depth in the sametaperingsurface,

gwe can easily produce air orts having their .the axis of the airnozzle.

axes directed to exactly t e same point on This is not so feasible'withdrilled air ports, as each port has to be drilled separately and even asllght wearing of the jig for guiding the drill will permit variationswhich show a considerable effect on the uniformity of the spray. Bycombining this accurate dimensioning and directin of the flattenin airjets with a uniform thickness of the tu ular air sheath, we are able tosecure the long desired uniformity of distribution of finely dividedpaint in a flat (or substantially fiat) spray.- Hence we eliminate themanual touching up of surfaces upon which a coating has been sprayed andlikewise avoid the spotty effects heretofore encountered on accountof'the s0- 'oalled off spray. Moreover, we accomplish these results byemploying a spray gun head construction comprising quite few parts andhaving each of these parts so designed that any reasonably skilledmachinist can readily manufacture them with a suf ficient degree ofaccuracy.-

However, we do not wish to be limited to the embodying of the variousfeatures of our invention in a hand appliance of the socalled spray guntype, nor to the use of our invention for spraying paints or varnishes.

We claim as our invention:

1.,In a-liquid spraying appliance, a body member having a forwardlytapering portion and a liquid passage extending through and coaxial withthe said tapering portion, a cap-like air nozzle having a forwardly ta-'pering bore extending into it from its rear end and tapered to fit thetapering portion of the body member, the air nozzle having an outletbore coaxial with and leading forwardly from its tapering bore andfreely hous ng the forward end of the tapering portlon of the bodymember, the air nozzle raving a forwardly tapering frustro-conical outerWall coaxial'with its tapering bore and hav ng passages leading to itsbore from the peripheral portion of the air nozzle behind its saidfrustro-conical wall; and a retaining collar secured to the body memberand having a part thereof spaced from the air nozzle to provide an airspace therebetween, the body member having an air passage leading to thesaid space, the collar havinga contracted front end tapered on its rearface to fit u on the frustro-conical wall of the air nozz e; thesecuring of the collar to the body member being such as to permitrelative 'movement thereof to allow a firm seating of the interfittingtapering parts of the body member, the air nozzle and the collar.

2. A liquid spraying appliance as er claim 1, in which the air nozzle is.provi ed on its frustro-conical wall with a pair of diametricallyopposite longitudinal grooves.

3. A liquid spraying appliance as er claim 1, in which the air nozzle isprovided on its frustro-conical wall with a pair of diametricallyopposite longitudinal rooves extending for the entire len th of t e saidwall, the lateral walls of eac groove being both parallel to a planediametric of the air nozzle and medial of the groove.

4:. A liquid spraying appliance constructed as per claim 1 and havmg apair of diametrically opposite air ports extending through the airnozzle from the said air space and directed toward a common pointforwardly of the air nozzle and on the axis of the nozzle.

5. A liquid spraying appliance including a liquid nozzle, an air nozzlefitted upon the liquid nozzle, the interfitting parts of the two nozzlescomprising forwardly tapering frustro-conical seats coaxial with thenozzles; an air confining collar having a portion thereof fitted uponthe air nozzle, the said collar portion and the part of the air nozzlefitted upon it comprising forwardly tapering frustro-conical seatscoaxial with the air nozzle and collar; and securing means rigidlyconnecting the collar to the liquid nozzle, the said means beingarranged to permit relative movement of the collar and liquid so as topermit an accurate alining and tight seating of the said interfittedparts during the fastening of the securing means.

6. A spray gun comprising a body memher, a liquid nozzle projectingforwardly from the body member and smaller in diameter than the adjacentpart of the body member, the liquid nozzle having a forwardly taperingfrnstro-conical portion and a cylindrical outlet part'extendingforwardly from the said portion and having a bore coaxial with the saidportion and part; an air nozzle having a forwardly tapering bore taperedto fit upon the frustro-conical portion of the liquid nozzle and havingcoaxial therewith an outlet bore larger in diameter than the outlet partof the liquid nozzle and housing the said part, the air nozzle alsohaving coaxial with its outlet bore a peripheral and forwardly taperingfrustro-conical wall; a retaining collar having a contracted forward endtapered on its rear face to fit the said wall. and having anotherportion freely housing the air nozzle to provide an air spacetherebetWeen, the body member having an air supply passage leading tothe said space, the air nozzle having ports connecting the said spacewith its'outlet bore and also having a pair of diametrically oppositepassages extending to the front of that nozzle from the said space anddirected toward a common point disposed on the axis of the air nozzleforwardly of that nozzle; and securing means operatively interposedbetween the collar and the body member, the said means being arranged topermit a relative rocking and shifting of the collar and body member soas to allow a'tight interfitting of the tapering air nozzle portionswith the tapering portions of the liquid nozzle and collar.

Signed at Chicago, Illinois, September 1nd, 1926.

BERT R. SAUSEN. EINAR E. OLSEN.

